JPH10239930A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the removal of a jam by moving a plurality of developing means to the side of the color image forming device together with an image carrier, and moving an image exposure means, disposed in an upper part, above the color image forming device, thereby exposing a transfer area. SOLUTION: An upper opening/closing cover 103 is opened around a support shaft 103a, an engagement member 124 is detached, and an exposure unit 120 is uncovered from the upper part of the device around the support shaft 122 of the lever 121, so that the upper part of the device is open. A process unit 300, composed of a drum unit 301 integrating a photoreceptor drum 10, scorotron electrifier 11, and cleaner 19 and a developing unit 302 integrating Y, M, C, and K developing devices 13 for separate colors both of which are connected with each other by a unit connection member 303, is pulled out along a guide plate 104. As a result, a transfer part 140 is uncovered and the transfer area is exposed. The connection member 303 is detached, the drum unit 301 is pulled out from the opening of the upper part of the device main body, and the transfer part 140 and a fixing device 17 are taken out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus such as a copying machine, a printer, a facsimile, etc., in which a charging means, an image exposing means and a plurality of developing means are arranged around an image forming body.
The present invention relates to an electrophotographic color image forming apparatus that forms a color image by superimposing a toner image on an image forming body by multiple rotations of the image forming body.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a multi-color image, the same number of image forming bodies, image exposing means, charging means, developing means and the like as colors required for image formation are provided. A color image forming apparatus in which a single color toner image formed on a transfer material is superimposed on a transfer material to form a color image, or the image forming body is rotated a plurality of times, and charging, image exposure and development for each color are repeated to form a color image on the image forming body There is known a color image forming apparatus or the like that forms a color image by superposing a toner image on a color image.

However, the above color image forming apparatus is provided with the same number of image forming bodies, image exposing means, charging means, developing means and the like as the number of colors required for image formation, and is capable of forming a single-color toner image formed on the image forming body. A color image forming apparatus that forms a color image by superimposing it on a transfer material requires a plurality of image forming bodies and a transfer material to be conveyed. On the other hand, a color image forming apparatus that rotates the image forming body a plurality of times, repeats charging, image exposure, and development for each color to form a color image by superimposing a toner image on the image forming body, Is limited to not more than the surface area of the image forming body, but has the advantage of reduced volume and is widely used as a color image forming apparatus.

[0004]

However, in the color image forming apparatus proposed above, the arrangement of the developing means, the image forming body and the image exposing means which requires a large volume for disposing a plurality of developing means is complicated. Becomes The present inventors have proposed a color image forming apparatus according to the above proposal,
The image exposing means is arranged at the upper part of the color image forming apparatus, and a plurality of developing means are arranged in parallel on the side of the image forming body with respect to the image forming body arranged at the center to reduce the volume. However, it is difficult to remove the developing means and the image forming body from the central portion of the color image forming apparatus, and to perform jam processing and exchange of the image forming body, the transfer means, and the fixing means. Further, in a configuration in which the image forming body is attached and detached from above, the image exposing means is arranged at a position where it does not interfere, and the upper side is largely opened. In this case, the main body of the apparatus is not reinforced and is weakened, which causes a problem in resist.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color image forming apparatus which solves the above-mentioned problems, has a strong apparatus main body structure, and allows easy jam processing and replacement of an image forming body, transfer means or fixing means.

[0006]

An object of the present invention is to provide a charging device, an image exposing device, and a plurality of developing devices around a drum-shaped image forming member, and to form a toner image by multiple rotations of the image forming member. In a color image forming apparatus, which is formed by being superimposed on a formed body and then collectively transferred to a transfer material by a transfer unit and fixed by a fixing unit, the image exposing unit is disposed above the image forming body, and Arranging the transfer means, further arranging the plurality of developing means in parallel on the side, and enabling the plurality of developing means to move sideways together with the image forming body, the image exposure means arranged on the upper part This is achieved by a color image forming apparatus characterized by opening the transfer area of the transfer means by moving upward (first invention).

Another object of the present invention is to dispose a charging device, an image exposing device, and a plurality of developing devices around a drum-shaped image forming member, and to form a toner image on the image forming member by multiple rotations of the image forming member. In a color image forming apparatus in which transfer is batch-transferred to a transfer material fed by a feeding unit after being formed by superimposition and fixed by a fixing unit, the image exposing unit is disposed above the image forming body. The transfer means is arranged at the lower part, and the plurality of developing means are arranged side by side further, so that the plurality of developing means can be moved to the side, and the upper image exposing means is moved upward. Accordingly, the present invention is achieved by a color image forming apparatus wherein the image forming body is detachably mounted on an upper portion of the color image forming apparatus (second invention).

[0008]

Embodiments of the present invention will be described below. The description of the present application does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope.

An image forming process and each mechanism of an embodiment of the color image forming apparatus of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view showing an embodiment of a color image forming apparatus according to the present invention, FIG. 2 is a top view showing a method of attaching an image exposure unit, and FIG. 3 is a method of attaching an image exposure unit. FIG. 4 is a diagram showing an embodiment of a method for removing an image forming body from a color image forming apparatus.

Referring to FIG. 1, a transfer material conveying belt 14a stretched between a driving roller 14d and a driven roller 14e.
Is rotated about the axis of the drive roller 14d to the position shown by the dotted line in FIG. 1, and the following image formation is performed in a state of being separated from the photosensitive drum 10. Also, the cleaning blade 19a of the cleaning device 19 is
The following image formation is performed in a state where the image is separated from the image.

A photosensitive drum 10 as an image forming body has a cylindrical base provided inside and a photosensitive layer such as a conductive layer, an a-Si layer or an organic photosensitive layer (OPC) formed on the outer periphery of the base. And is rotated clockwise as indicated by the arrow in FIG. 1 in a grounded state.

The photosensitive drum 10 is driven and rotated, and in order to eliminate the history of the photosensitive drum 10 up to the previous print, uniform exposure is performed by a uniform exposure device 111 as a discharging device before charging, for example, a light emitting diode. Then, the charge on the peripheral surface of the photoconductor is removed, and the charge in the previous printing is removed.

Scorotron charger 11 as charging means
Are used in image forming processes of yellow (Y), magenta (M), cyan (C) and black (K), and face the photosensitive drum 10 in a direction orthogonal to the moving direction of the photosensitive drum 10. Attached to the photosensitive drum 10
And a control grid maintained at a predetermined potential with respect to the above-described organic photoreceptor layer, and a corona discharge electrode 11a, for example, using a saw-tooth electrode, and a corona discharge having the same polarity as that of the toner. (Electrification) to apply a uniform potential to the photosensitive drum 10. As the corona discharge electrode 11a, a wire electrode or a needle electrode may be used.

The photosensitive drum 10 is a scorotron charger 1
After the peripheral surface is uniformly charged by 1, image exposure based on an image signal is performed by an exposure unit 120 as an image exposure unit, and a latent image is formed on the photosensitive drum 10.

An exposure unit 120 as an image exposure means includes a semiconductor laser as a light emitting element (not shown) and a rotary polygon mirror 12 for rotating and scanning a laser beam emitted from the semiconductor laser.
0a, collimator lens 120b, fθ lens 120
c, a reflecting mirror 120d, etc., and the laser beam is rotationally scanned by a rotating polygon mirror 120a, and a collimator lens 120b, an fθ lens 120c, a reflecting mirror 120d
After that, image exposure based on the image signal is performed in the main scanning direction of the rotating photosensitive drum 10 to form a latent image on the photosensitive drum 10. The exposure unit 120 is arranged above the photosensitive drum 10.

On the sides of the photoreceptor drum 10, developing means filled with a developer composed of a toner such as yellow (Y), magenta (M), cyan (C), and black (K) and a carrier are used. A developing unit 13 for each color is provided. First, development of the first color (for example, yellow) is performed by the developing sleeve 131.

The developing unit 13 converts the electrostatic latent image on the photosensitive drum 10 formed by the charging by the scorotron charger 11 and image exposure by the exposure unit 120 by a non-contact developing method by applying a developing bias voltage. In a non-contact state, development is performed by reversal development using a toner having the same polarity as the charged polarity (in the present embodiment, the photosensitive drum is negatively charged and has a negative polarity).

The developing unit 13 is moved to a predetermined distance from the photosensitive drum 10 by an abutting roller (not shown), for example, 100 μm.
Is maintained in a non-contact state with a gap of about 500 μm.
In the developing operation of the developing device 3, a developing bias in which a DC voltage or an AC voltage is superimposed is applied to the developing sleeve 131, and a jumping development is performed by a one-component or two-component developer accommodated in the developing device, thereby forming a transparent conductive material. A non-contact reversal development is performed in which a DC bias of the same polarity as the toner (in this embodiment, a negative polarity) is applied to the negatively charged photoconductor drum 10 that grounds the layer, and the toner adheres to the exposed portion. At this time, the precision of the development interval needs to be about 20 μm or less in order to prevent image unevenness.

After the development of the first color is completed, the image process of the second color (for example, magenta) is started, and the photosensitive drum 10
Are uniformly charged by the scorotron charger 11, and a latent image based on the image data of the second color is formed by the exposure unit 120. At this time, static elimination by the uniform exposure device 111 performed in the image forming process for the first color is not performed. The development with the magenta developer of the second color is performed by the developing sleeve 131. The development is performed by non-contact reversal development by applying a development bias in which a DC voltage or an AC voltage is further superimposed between the development sleeve 131 and the photosensitive drum 10.

The same image forming process as that for the second color is performed for the third color (cyan) and the fourth color (black), and the four color toner images are superposed and developed on the photosensitive drum 10.

The recording paper P, which is a transfer material, is sent out by a feed roller 15a from a paper feed cassette 15, which is a transfer material storage means, is fed by a feed roller 15b, and is conveyed to a timing roller 15c.

The transfer section 140 as a transfer means is constituted by a drive roller 14d, a driven roller 14e, a transport belt 14a, and a transfer device 14c provided opposite to the photosensitive drum 10 with the transport belt 14a interposed therebetween. A transfer area 14b is provided to face the photoconductor drum 10. The transfer unit 140 is arranged below the photosensitive drum 10.

The transport belt 14a is rotated about the axis of the drive roller 14d to the position shown by the solid line in FIG. 1 so that the toner image formed on the photosensitive drum 10 and the transfer area 14b are synchronized. Is brought into contact with the photosensitive drum 10.

The recording paper P is fed to the transfer area 14b in synchronization with the toner image on the photosensitive drum 10 by driving the timing roller 15c.

The toner image on the peripheral surface of the photosensitive drum 10 is collectively collected by the transfer unit 14c to which a voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied.
Is transferred to

The recording paper P is separated from the transport belt 14a by the curvature of the drive roller 14d, and is transported to a fixing device 17 as a fixing unit composed of two rollers.
By applying heat and pressure between the fixing roller 17a and the pressure roller 17b, the toner adhered on the recording paper P is fixed, sent by the discharge roller 18 and discharged to a tray outside the apparatus.

The transport belt 14a is again driven by the drive roller 14d.
Is rotated to the position indicated by the dotted line in FIG. Cleaning blade 1
9 a is brought into contact with the photosensitive drum 10, and the toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is transferred to the cleaning device 1.
9 and is scraped off into the cleaning device 19 by a cleaning blade 19a made of a rubber material abutting on the photosensitive drum 10, and is collected by a screw 19b into an unshown toner container. The cleaning blade 19a is separated from the photosensitive drum 10 again, and the photosensitive drum 10 from which the residual toner has been removed by the cleaning device 19 is de-charged by the exposure of the uniform exposure device 111 to the peripheral surface of the photosensitive drum, and is charged in the previous printing. Is removed and uniformly charged by the scorotron charger 11, and the next image forming cycle is started.

According to FIGS. 1 to 3, reference numeral 103 denotes the support shaft 1.
It is an upper opening / closing lid that can be opened / closed with 03a as a rotation center.

A support shaft 122 of the lever 121 is provided on the front and rear side plates 101 and 102 in FIG. 1 of the apparatus main body, and the exposure unit 120 is rotatable around the support shaft 122 of the lever 121 as a rotation support. An arm 123 extends from the end of the housing of the exposure unit 120 opposite to the lever 121, and a circular engagement member 124 having an H-shaped cross section is attached to both ends of the arm 123. An engaging member 124 is fitted in an engaging shaft 124a at the center of the H-shape into engaging grooves 101a, 102a provided substantially at the center of the upper ends of the front and rear side plates 101, 102 of the apparatus main body. Fixed to By the arm 123 whose upper center is substantially integrated with the engagement member 124, the arm 123 is stretched over the housing as a stay, and the main body of the color image forming apparatus whose upper center is opened is reinforced. The main body of the apparatus is reinforced by the arms 123 fitted into the side plates 101 and 102, so that the registration of the superposed image by the image exposure means can be performed with high accuracy.

Referring to FIG. 4, the upper opening / closing lid 103 is first opened with the support shaft 103a as a fulcrum. The engagement grooves 101a,
The engaging member 124 is detached from 102a, and the exposure unit 120 is opened from the upper part of the apparatus using the support shaft 122 of the lever 121 as a fulcrum, and the upper part of the apparatus is opened.

The guide plate 104 is opened with the support shaft 104a as a fulcrum, and comes into contact with a stopper 105 stretched between the side plates 101 and 102 to form a guide plane. Photoconductor drum 1
0, scorotron charger 11 and cleaning device 19
And a developing unit 3 in which developing units 13 for each of Y, M, C and K are integrated.
2 are connected by a unit connecting member 303 to form a process unit 300, and the process unit 300 is pulled out on the guide plate 104 to the right in FIG. 4. In this state, the transfer unit 140 as a transfer unit is opened, and the transfer area 14b is opened, so that the jam processing is facilitated.

The coupling member 303 is removed, the drum unit 301 is pulled out from the opening at the top of the apparatus main body, and maintenance and replacement of the drum unit 301 are performed. Similarly, the not-shown locking member is removed from the opening at the top of the apparatus, the transfer unit 140 or the fixing device 17 is taken out, and the transfer unit 140 or the fixing device 17 is maintained or replaced.

In the above description, it is possible to provide a handle 301a indicated by a dashed line in FIG. 4 on the drum unit 301 so that the drum unit 301 can be easily pulled out.

As described above, since the upper part of the apparatus main body is opened, it is easy to replace the image forming body, the transfer means or the fixing means.

FIG. 5 shows another embodiment of a method for removing an image forming body from a color image forming apparatus.

The image forming process, the structure and the opening and closing mechanism of the image exposure means are the same as those described with reference to FIGS.

As shown in FIG. 5, the upper opening / closing lid 103 is first opened with the support shaft 103a as a fulcrum. Engagement groove 101
The engaging member 124 is removed from the levers 121 and 102a.
The exposure unit 120 is opened from the top of the apparatus with the support shaft 122 as a fulcrum, and the top of the apparatus is opened.

The guide plate 104 is opened with the support shaft 104a as a fulcrum, and comes into contact with a stopper 105 stretched between the side plates 101 and 102 to form a guide plane. Photoconductor drum 1
The developing unit 302, which integrates the developing units 13 for the respective colors of Y, M, C, and K arranged on the side of the
04 is drawn rightward in FIG. A drum unit 301 is provided integrally with the photosensitive drum 10, the scorotron charger 11 and the cleaning device 19, and the central axis 10a of the photosensitive drum 10 is connected to both side plates 101 and 102.
The drum unit 301 is pulled out upward using the guide grooves 101b and 102b provided in the drum as guides. In this state, the transfer unit 140 as a transfer unit is opened, and the transfer area 14b is opened, so that the jam processing is facilitated. Also,
A feed guide plate 15d which constitutes a feeding unit by integrating a roller member facing the timing roller 15c is opened by the timing roller 15c, and the jam processing becomes easier. A handle 301a indicated by a chain line in FIG. 5 may be provided on the drum unit 301 to facilitate pulling out of the drum unit 301.

The drum unit 301 is pulled out from the opening in the upper part of the apparatus main body, and maintenance and replacement of the drum unit 301 are performed. After replacement or maintenance, the drum unit 301 is fitted with the center shaft 10a of the photosensitive drum 10 into the guide grooves 101b and 102b, and
b, 102b are inserted as guides,
Positioning pins 101c provided on the central side of
The positioning groove 301b provided in the housing of the drum unit 301 is fitted into the drum 102c, the drum unit 301 is positioned, and the drum unit 301 is loaded into the apparatus main body. With the developing unit 302 being moved from the photosensitive drum 10 as an image forming body, the photosensitive drum 10 is provided detachably from the upper portion of the apparatus main body.

With the photoreceptor drum 10 removed from the upper part of the apparatus main body, the not-shown locking member is removed from the opening in the upper part of the apparatus, and the transfer unit 140 or the fixing device 17 is taken out.
Maintenance or replacement of the transfer unit 140 or the fixing device 17 is performed.

As described above, since the upper part of the apparatus main body is opened, the transfer means or the fixing means can be easily replaced.

[0042]

According to the first aspect of the present invention, the plurality of developing means can be moved to the side of the color image forming apparatus together with the image forming body, and the image exposing means disposed on the upper side is located above the color image forming apparatus. By moving and opening the transfer area, jam processing is facilitated.

According to the second aspect, replacement of the image forming body, transfer means or fixing means becomes easy.

According to the third aspect, the main body of the color image forming apparatus whose upper center is opened is reinforced and the main body structure is strengthened. By reinforcing the apparatus main body, registration at the time of forming a superimposed image by the image exposure means is performed with high accuracy.

According to the fourth or fifth aspect, the plurality of developing means can be moved to the side of the color image forming apparatus.
By moving the upper image exposure unit above the color image forming apparatus and attaching and detaching the image forming body, the jam processing is facilitated.

According to the sixth aspect, the transfer means or the fixing means can be easily replaced.

According to the seventh aspect, the main body of the color image forming apparatus whose upper center is opened is reinforced and the main body structure is strengthened. By reinforcing the apparatus main body, registration at the time of forming a superimposed image by the image exposure means is performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating an embodiment of a color image forming apparatus of the present invention.

FIG. 2 is a top view illustrating a method of attaching an image exposure unit.

FIG. 3 is a perspective view showing a method of attaching an image exposure unit.

FIG. 4 is a diagram illustrating an embodiment of a method of removing an image forming body from a color image forming apparatus.

FIG. 5 is a diagram illustrating another embodiment of a method for removing an image forming body from a color image forming apparatus.

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum 11 scorotron charger 13 developing device 14a transport belt 15d feeding guide plate 17 fixing device 120 exposure unit 123 arm 124 engaging member 140 transfer unit P recording paper

Claims (7)

[Claims] A charging means provided around a drum-shaped image forming body;
An image exposing unit and a plurality of developing units are arranged, and the toner image is superimposed and formed on the image forming unit by multiple rotations of the image forming unit, and then collectively transferred to a transfer material by a transfer unit and fixed by a fixing unit. In the color image forming apparatus, the image exposing unit is disposed above the image forming body,
The transfer means is arranged at a lower part, the plurality of developing means are further arranged side by side, and the plurality of developing means are movable sideways together with the image forming body, and the image exposure arranged at the upper part A color image forming apparatus, wherein a transfer area of the transfer unit is opened by moving the unit upward. 2. The color image forming apparatus according to claim 1, wherein the image forming body, the transfer unit, or the fixing unit is replaced while the transfer area is open. 3. The color image forming apparatus according to claim 1, wherein said image exposing means is integrated with stays on both side plates of said color image forming apparatus main body. 4. A charging means around a drum-shaped image forming body,
An image exposing unit and a plurality of developing units are arranged, and the toner image is superimposed on the image forming unit by multiple rotations of the image forming unit, and then collectively transferred to the transfer material fed by the feeding unit by the transfer unit. In a color image forming apparatus for transferring and fixing by a fixing unit, the image exposing unit is disposed above the image forming body,
Disposing the transfer means at a lower part, further arranging the plurality of developing means in parallel on the side, enabling the plurality of developing means to move sideways, and moving the upper image exposure means upward Wherein the image forming body is attached to and detached from an upper part of the color image forming apparatus. 5. The color image forming apparatus according to claim 4, wherein said image forming body is taken out and said feeding means is opened. 6. The color image forming apparatus according to claim 4, wherein the transfer unit or the fixing unit is replaced after taking out the image forming body. 7. The color image forming apparatus according to claim 4, wherein said image exposing means is integrated with stays on both side plates of said color image forming apparatus main body.